The overall objective of the project is the prediction of resistance to drug use and drug abuse among adolescents (ages 12-18). The dependent variable will be studied through the critical incident technique, and a multidimensional drug use criteria will be derived. In this technique, adolescents and others knowledgeable about adolescent drug use relate experiences adolescents have had with drugs. Content analysis of these incidents reveals dimensions or categories of drug related behavior. This information can then be used in developing both dependent and independent variable measures. These measures will then be administered to a large sample of junior and senior high students (approximately 20,000) in two metropolitan areas. These data will be analyzed by such techniques as multiple discriminant function, moderator, configural, or acturial patterns analyses. The major thrust of the analysis will be to develop differential prediction systems for theoretically or empirically separate subgroups of adolescents.